Macro Calculator - Free Online Tool

Calculate your optimal daily macronutrient intake based on your body stats, activity level, and fitness goals

Welcome to our free Macro Calculator (Macronutrient Calculator), a comprehensive tool designed to help you determine the ideal daily intake of protein, carbohydrates, and fat based on your personal body stats, activity level, and fitness goals. Whether you are trying to lose weight, build muscle, maintain your current physique, or simply eat a more balanced diet, understanding your macronutrient needs is the foundation of effective nutrition planning. Macronutrients, often referred to as macros, are the three primary nutrients your body needs in large quantities: protein, carbohydrates, and fat. Each macronutrient serves a distinct purpose. Protein is essential for building and repairing muscle tissue, supporting immune function, and producing enzymes and hormones. Your body requires approximately 4 calories of energy for every gram of protein consumed. Carbohydrates are your body's preferred energy source, fueling everything from brain function to intense physical exercise. Like protein, carbohydrates provide about 4 calories per gram. Fat is critical for hormone production, nutrient absorption, cell membrane integrity, and long-term energy storage. Fat is the most calorie-dense macronutrient, providing 9 calories per gram. This calculator uses three scientifically validated formulas to estimate your Basal Metabolic Rate (BMR): the Mifflin-St Jeor equation (developed in 1990 and recommended by the American Dietetic Association as the most accurate), the Revised Harris-Benedict equation (originally published in 1919 and revised in 1984), and the Katch-McArdle formula (which uses lean body mass for greater accuracy in individuals who know their body fat percentage). Your BMR is then multiplied by an activity factor to determine your Total Daily Energy Expenditure (TDEE), which represents the total number of calories you burn in a day. Once your TDEE is established, the calculator applies your selected goal (maintain weight, lose weight at various rates, or gain weight) to determine your target daily calorie intake. It then distributes those calories across protein, carbohydrates, and fat according to your chosen diet preset. We offer six popular preset ratios: Balanced (40/30/30), Low Fat (60/25/15), Low Carb (25/40/35), High Protein (30/40/30), Ketogenic (5/25/70), and Zone Diet (40/30/30). You can also create a fully custom macro ratio by entering your own percentages. Additional features include per-meal breakdowns for 2 to 6 meals per day, a direct calorie input mode for users who already know their TDEE, visual donut charts showing your macro split, horizontal bar comparisons of all diet presets, and the ability to export your results to CSV or print them. All calculations run entirely in your browser with no data stored or transmitted, ensuring complete privacy.

Understanding Macronutrients

Macronutrients are the three categories of nutrients that provide calories and energy to your body: protein, carbohydrates, and fat. The ratio in which you consume them can significantly impact your body composition, energy levels, and overall health.

Protein: The Building Block

Protein provides 4 calories per gram and is essential for muscle repair, immune function, and enzyme production. Research suggests 0.7-1.0 grams per pound of body weight for active individuals, and up to 1.2-2.0 grams per kilogram for those focused on muscle gain or weight loss.

Carbohydrates: Your Primary Fuel

Carbohydrates provide 4 calories per gram and serve as your body's preferred energy source. They fuel brain function, support intense exercise, and help regulate blood sugar levels. The USDA recommends 45-65% of total calories come from carbohydrates for most adults.

Fat: Essential for Health

Fat provides 9 calories per gram and is vital for hormone production, vitamin absorption (A, D, E, K), and cellular health. The USDA recommends 20-35% of total calories from fat, with emphasis on unsaturated sources like olive oil, nuts, and fatty fish.

Formulas

Protein Grams from Calories

Protein (g) = (Total Calories × Protein%) ÷ 4

Protein provides 4 calories per gram. Divide your protein calorie allocation by 4 to get the daily gram target.

Carbohydrate Grams from Calories

Carbs (g) = (Total Calories × Carb%) ÷ 4

Carbohydrates provide 4 calories per gram. Divide your carb calorie allocation by 4 to get the daily gram target.

Fat Grams from Calories

Fat (g) = (Total Calories × Fat%) ÷ 9

Fat provides 9 calories per gram, making it the most calorie-dense macronutrient. Divide your fat calorie allocation by 9 to get the daily gram target.

Mifflin-St Jeor BMR (Male)

BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age) + 5

The most accurate BMR formula for the general population, recommended by the American Dietetic Association. For females, subtract 161 instead of adding 5.

Reference Tables

Common Diet Macro Split Ratios

Popular macronutrient ratio presets expressed as percentage of total daily calories (Carbs / Protein / Fat).

Diet Type	Carbs %	Protein %	Fat %	Best For
Balanced	40%	30%	30%	General health, maintenance
Low Fat	60%	25%	15%	Heart health, low-fat diets
Low Carb	25%	40%	35%	Fat loss, blood sugar control
High Protein	30%	40%	30%	Muscle building, weight loss
Ketogenic	5%	25%	70%	Ketosis, epilepsy management
Zone Diet	40%	30%	30%	Athletic performance, inflammation control

Recommended Daily Protein Intake by Activity Level

Protein intake guidelines in grams per kilogram of body weight per day, based on activity and goals.

Activity Level	g/kg/day	Example (70 kg person)
Sedentary adult	0.8	56 g/day
Recreational exerciser	1.0–1.2	70–84 g/day
Endurance athlete	1.2–1.4	84–98 g/day
Strength / power athlete	1.6–2.0	112–140 g/day
Fat loss (calorie deficit)	1.6–2.4	112–168 g/day
Elderly (65+)	1.0–1.2	70–84 g/day

Worked Examples

Balanced Diet Macros for 2,000 Calories

A person has a TDEE of 2,000 calories and wants to use the Balanced preset (40% carbs, 30% protein, 30% fat) at maintenance.

Protein calories: 2,000 × 0.30 = 600 calories

Protein grams: 600 ÷ 4 = 150 g

Carb calories: 2,000 × 0.40 = 800 calories

Carb grams: 800 ÷ 4 = 200 g

Fat calories: 2,000 × 0.30 = 600 calories

Fat grams: 600 ÷ 9 = 66.7 g

Daily targets: 150 g protein, 200 g carbs, 67 g fat. Split across 4 meals: 37.5 g protein, 50 g carbs, and 16.7 g fat per meal.

Keto Diet Macros for Weight Loss

A 180 lb male with a TDEE of 2,500 calories wants to lose 1 lb/week on a Ketogenic diet (5% carbs, 25% protein, 70% fat).

Weight loss deficit: 2,500 - 500 = 2,000 calories/day

Carb calories: 2,000 × 0.05 = 100 calories → 100 ÷ 4 = 25 g carbs

Protein calories: 2,000 × 0.25 = 500 calories → 500 ÷ 4 = 125 g protein

Fat calories: 2,000 × 0.70 = 1,400 calories → 1,400 ÷ 9 = 155.6 g fat

Daily keto targets at a 500-calorie deficit: 25 g carbs, 125 g protein, 156 g fat. The very low carb intake (under 50 g) should induce ketosis within a few days.

How to Use the Macro Calculator

Enter Your Body Stats

Select your sex, enter your age, choose imperial or metric units, and input your weight and height. If you already know your daily calorie needs, switch to Direct Calorie Input mode instead and enter your TDEE directly.

Set Activity Level and Goal

Choose the activity level that best matches your typical week, from sedentary to extra active. Then select your weight goal: maintain, lose weight at a mild, standard, or extreme rate, or gain weight at a mild, standard, or extreme rate.

Choose a Diet Preset or Custom Ratios

Select from six popular diet presets (Balanced, Low Fat, Low Carb, High Protein, Ketogenic, Zone) or create a custom ratio by entering your own protein, carb, and fat percentages that sum to 100%. Use Advanced Settings to change the BMR formula.

Review Your Results

View your daily macro targets in grams and calories, see the visual donut chart of your macro split, compare diet presets side-by-side, and check your per-meal breakdown. Export results to CSV or print them for your records.

Frequently Asked Questions

What are macros and why do they matter for weight loss?

Macros, short for macronutrients, are the three main categories of nutrients your body needs in large quantities: protein, carbohydrates, and fat. While total calorie intake determines whether you gain or lose weight, macronutrient ratios affect your body composition, energy levels, satiety, and metabolic health. For example, higher protein intake during a calorie deficit helps preserve lean muscle mass and keeps you feeling full longer, while adequate fat intake supports hormone production. Tracking macros rather than just calories gives you more control over whether you lose fat versus muscle, how energized you feel during workouts, and how well your body functions during a diet.

Which diet preset should I choose for my goals?

The best diet preset depends on your goals and lifestyle. For general health and fitness, the Balanced preset (40% carbs, 30% protein, 30% fat) works well for most people. If you are focused on fat loss while preserving muscle, High Protein (30% carbs, 40% protein, 30% fat) or Low Carb (25% carbs, 40% protein, 35% fat) are popular choices. The Ketogenic preset (5% carbs, 25% protein, 70% fat) is designed for those pursuing a keto diet, which requires severely limiting carbohydrates to induce ketosis. The Zone Diet (40/30/30) is similar to Balanced and favored by many athletes. Start with Balanced if unsure, and adjust based on how your body responds over 2-4 weeks.

How accurate is this macro calculator?

This calculator provides science-based estimates using three well-established BMR formulas. The Mifflin-St Jeor equation, our default, is accurate within approximately 10% for most healthy adults according to the American Dietetic Association. However, individual metabolism varies based on genetics, body composition, hormonal health, medications, sleep quality, and stress levels. The calculator gives you an excellent starting point, but you should treat the results as an initial target and adjust based on real-world results over 2-4 weeks. If you are not seeing expected changes in weight or body composition, try adjusting calories by 100-200 in either direction while keeping your macro ratios consistent.

What is the difference between Mifflin-St Jeor, Harris-Benedict, and Katch-McArdle formulas?

The Mifflin-St Jeor equation (1990) is the most widely recommended BMR formula, using weight, height, age, and sex. It is accurate for approximately 82% of people within a 10% margin. The Revised Harris-Benedict equation (1919, revised 1984) uses the same variables but was developed with older population data and tends to slightly overestimate BMR. The Katch-McArdle formula takes a different approach by using lean body mass instead of total body weight, making it potentially more accurate for individuals who know their body fat percentage, especially those who are very lean or very muscular. If you know your body fat percentage, Katch-McArdle may give you the most personalized result.

How many meals per day should I eat for optimal results?

Research shows that total daily macro and calorie intake matters far more than meal frequency for body composition and weight management. Whether you eat 2, 3, 4, 5, or 6 meals per day, your results will be similar as long as total intake remains the same. That said, meal frequency can affect practical factors like hunger management, energy levels throughout the day, and convenience. Some people prefer 3 larger meals for simplicity, while others find 5-6 smaller meals help control appetite and maintain steady energy. Athletes and those building muscle may benefit from spreading protein intake across 4-5 meals to maximize muscle protein synthesis. Choose a meal frequency that fits your schedule and helps you consistently hit your daily macro targets.

Is it safe to follow an extreme weight loss plan?

Extreme weight loss plans creating a 1000-calorie daily deficit should be approached with caution and ideally under medical supervision. While a 2 lb per week loss rate can be safe for individuals with significant weight to lose, it can cause muscle loss, metabolic adaptation, nutrient deficiencies, fatigue, and hormonal disruption in others. Most nutrition experts recommend a moderate deficit of 500 calories per day (approximately 1 lb per week) as the safest sustainable approach. Never eat below your BMR for extended periods, as this can significantly slow your metabolism. If you have existing health conditions, are pregnant or nursing, or are under 18, consult a healthcare provider before starting any calorie-restricted diet.